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Virtual Reality
Lecture 4. Human Factors : Psychological and Cognitive Issues
고려대학교 그래픽스 연구실
Contents
• Presence and Reality• Human Visual System• Human Auditory System• Other Perceptual systems• Cognitive system
Presence and Reality
1. Tele-presence and Virtual presence2. AIP cube3. Model P4. Measuring reality5. Philosophical considerations
1. Tele-presence
INDEPENDENT VARIABLES DEPENDENT MEASURES
Experimental determination of presence,learning efficiency, and performance.
extent of
sensory
information
control of
sensors
PRINCIPAL
DETERMINANTS
OF PRESENCEability to
modify
environment
task difficultyMAJOR
TASK
VARIABLES
degree of
automation
sense of presence subjective rating objective measures
training efficiency
task performance
2. AIP Cube
• Zeltzer (1992)
• A model for describing, categorizing, comparing various VEs, rather than what contitutes the sense of presence.
• Three components– autonomy– interaction– presence
autonomy and Interaction
• Autonomy– the ability of a computation model to act and react to simulat
ed events and stimuli• 0 : passive, geometric model• 1 : most sophisticated, knowledge based virtual agent• 0.x : physics-based model
• Interaction– the degree of access to model parameters at runtime
• 0 : "batch" processing - no interaction at runtime• 1 : comprehensive, realtime access to all parameters
autonomy vs. interaction
• autonomy - interaction plane– Two axes are complementary (or inter-
related).– The level of interaction is (inversely)
determined by the degree of autonomy.
• degree of freedom problem– Providing direct assess to many parameters
is not necessarily productive.
presence
– A rough, lumped measure of the number and fidelity of available sensory input and output channels
– Measure of the Selective Fidelity
– must consider the degree of match between the sensory data and mental model.
– may consider sensory substitution (e.g., auditory output, instead of haptic).
autonomy, interaction, presence
(0,0,0)
(1,0,0) (1,1,0)
(0,1,0)
(0,1,1)(0,0,1)
(1,0,1)
Autonomy
Interaction
Presence
DigitalShakespeare
Task LevelGraphical Simulation
ConventionalAnimationSystemsca. 1990
"Virtual Reality"
(1,1,1)
Interesting possibilities
0 0 0 batch processing of simple models on plotter0 0 1 non-interactive virtual tour0 1 0 animation systems0 1 1 commercial virtual environment1 0 0 high precision simulation 1 0 1 "Virtual Theater"1 1 0 MUD(?)1 1 1 truly a Virtual Reality
Autonomy
InteractionPresence Typical System
3. Model P
• Perception– visual– auditory– tactlie– etc.
• Interaction– self– environmental– social
• Model– geometry– kinematics– dynamics– behavioral– cognitive– emotional
• Factors that affect the quality of perception– inclusiveness– surroundedness– extensiveness– vividness– synchronization
4. Measuring reality
(1) Psychological and subjective measures(2) Psychophysical measures(3) Physiological measures(4) Performance measures(5) Reflex response
(1) Psychological and subjective measures• procedure
i) Scale rating along a uni-directional axis.ii) Compute the psychological distance
• Ex. NASA TLX scale– mental load = f (mental demand, physical demand,
temporal demand, performance, effort)• Ex. Presence assessment
• Ex. factorial studies
• Ex. Discrimination between a real and a virtual worlds
P (judged “real” | actually real)P (judged “real” | actually virtual)
idea: image quality virtual < real virtual = real + noise
(2) Psycho-physical measures
• measures more “local” parameters.
• Types of classic problems– sensory threshold– recognition– discrimination– scale
(3) Physiological measures
• classes– cardiovascular– respiratory– nervous– sensors– blood chemistry
(4) Performance measures
• Examples– # of errors– time spent– accuracy
• Assumption: presence = f (performance)
• But, we may decrease presence intentionally in order to increase performance.
(5) Reflex response
• Response to unexpected / threatening stimuli.
• Socially-conditioned response
• effects of prolonged exposure
5. Philosophical considerations
• Theories on reality– Plato– Leibniz– Goodman– Popper